Traffic protection apparatus



Aug. 9, 1949. E. SPRAY TRAFFIC PROTECTION. APPARATUS Filed Feb. 20, 1947 INVENTOR. Left jvray. BY

HIS A T TOHNE'Y.

Patented Aug. 9, 15349 7 UNITED.- STATES (PATENT OFFICE,

TRAFFIC PROTECTION APPARATUS Lester E. Spray, WilkinsburgPal, assignor to The Union Switch & Signal company, Swissvale, Pa., a corporation of Pennsylvania Application February 20, 1947, Serial No. 729,827

My invention relates to trafiic protection apparatus, and particularly to apparatus for providing crossover protection for trains moving along railway tracks which are connected with each other by a crossover track through'handoperated track switches.

A requisit for crossover protection apparatus is that it must be so arranged. that a car or locomotive, when occupying a crossover such, for example, as one connecting two main tracks, while the switches are in the normal position for train movements along the main tracks, will cause a signal for each main track to indicate stop if the car or locomotive is within fouling distance of that main track. In crossover pro-- tection schemes embodying track circuits, one characteristic should therefore be high shunting sensitivity in order to insure that the cross over track circuits will be shunted if the crossover track has high contact resistance due to infrequency of train movements overthe crossover.

One feature of my invention is the provision of means for utilizing one-ha1f of an'alternating current wave supplied to a track circuit for energizing a direct current track relay and for utilizing the other half of the wave supplied to this track circuit for energizing a second track circuit through a transformer. With this arrangement the two track circuits, although supplied with energy from the same sourcaare insulated from each other. Trackcircuits arranged in accordance with my invention, to pass half waves of alternating current constituting pulsating unidirectional current, have high shunting sensitivity.

1 shall describe one form of apparatus embodying my invention, and shall then point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic view showin one form of apparatus embodying my invention, in which a crossover track is divided into two sections, one of which is sup- 6 Claims. (Cl. 246-219) plied with alternating current from a source 7 connected in multiple with a direct current relay, and. the other of which is supplied with cur rent from the secondary winding of a transformer, the primary windin of which is connected through an asymmetric unit across the rails of the first track section.

Similar reference characters refer, to similar parts in the drawing. v

Referring to the drawing, a stretch of railway is shown comprising two main tracks, designated by the reference characters IT and 2T, interconnected by a crossover track, designated by the reference character 3T, through hand-operated track switches IW and 2W. A pair of insulated joints 4 and 5 is provided in each end of track 3T. Joint 4 of each of these pairs is located in the frog side of its end of track 3T between the rails of the adjacent main track, and joint 5 of each pair is located in the other side of the crossover track adjacent the heel of the switch at its end of track 3T. Track ST, is divided into two sections ab and b--c by a third pair of insulated joints 6 in the rails of this track at an intermediate point between the two pairs of in sulated joints 4 and 5.

Section 11-11 is provided with a track circuit includin a suitable source of alternating current, shown as a transformer EF, the primary winding m of which is energized by alternating current from terminals BX and NX, and the secondary winding d of which is connected through impedance 8 and in multiple with a direct current track'relay IXR across the rails of one end of the section, and also includin the primary winding m of a second transformer 2F connected through an asymmetric unit IC across the opposite end of the section.

Section 11-0 is provided with a trackscircuit including the secondary winding (1 of transformer 2F connected through an impedance 9 in multi ple with a second direct current track relay ZXR across the rails of section bc adjacent insu lated joints 6, and also including a second asymmetric unit 20 connected across the rails of section b-c adjacent the opposite end of the section. Each of the asymmetric units I C and 26 may be of any suitable design such, for example, as

the wel1-known copper oxide half-wave rectifier.

the left, as shown in the drawing, which I shall assume is the westbound direction. A second signal 2S is shown for governing traflic move} ments in the opposite or eastbound direction into the section of track 2T. Signals IS and 2S may 'be of any suitable design such, for example, as .the semaphore orsearhlight type. andZS are controlled by circuits including con- Signals IS 3 ,tacts of relays lR and 2R, respectively, and also including contacts of relays IXR and ZXR.

I shall now describe in detail the circuits and operation of the apparatus shown in the accompanying drawing.

As shown in the drawing, all parts of the apparatus are in the normal condition, that is, each of the switches IW and 2W is in the normal position for a train movement along main track IT or 2T, respectively; each of the track relays IR, 2R, IXR. and ZXR is energized; and each of the signals iS and 28 is displaying aproceed indication.

In the circuit for section a-b, one-half of the alternating current wave supplied by secondary Winding d of transformer IF passes from secondary winding :1, through the windingof relay IXR, and impedance 8, back to secondary winding d. Current from this half wave is blocked by asymmetric unit [6 from flowing through winding m of transformer 2F. Current from the other half of the alternating current wave passes from secondary winding d of transformer 1 F, through impedance 8, rail 3b of section a -b, primary winding m of transformer 2F, asymmetric unit [0, and rail 3a of section ab, back to secondary winding dof transformer I F. The impedance of this path is low compared to that of :the windin of relay IXR, so that very little of this other .half ofthe alternating current wave passes through the winding of relay IXR.

.In thecircuit for section bc, one-half of the alternating current wave from transformer 2F passes from secondary winding d of transformer 2F through the winding of relay 2XR, and impedance 9, back to secondary winding (1 of transformer 2F. This half wave is blocked by asymmetric unit 20 from passing across the rails of track 3T through unit 20. The other half of the same alternating current "wave passes from secondary winding d of transformer 2F, through impedance 9, rail 3a of section bc, asymmetric unit 2C, and rail 31) of section b-c, back to secondary winding 11 of transformer 2F.

As shown in the drawing, contacts 10, II and l2 of relays IXR, ZXRand IR, respectively, are closed in a circuit for clearing signal is. Similarly, contacts it, Hi and I of relays ZXR, IXR and 2R, respectively, are closed in a circuit for controlling signal 28.

I shall assume that, with apparatus arranged as shown in the drawing, a trainman reverses switches IW and 2W for a train to move over track 3T. While a train occupies section are-b,

relay IXR is shunted, causing this relay to be I deenergized, and .winding m of transformer 2F is also shunted, causing relay 2XR to be deenergized. While a train occupiessection b- -c, relay :ZXR is shunted, causing this relay to be deenergized. When relay IXR is deenergized, thecir- :cuits for signals IS and 2S will be open at conttacts 1'0 and [4, respectively, of thisrelay,-and, when relay g2XR is deenergized, the circuits for signals is andZS will be open at contacts ,II and I3, respectively, of relay ZXR, causing signals I'Sand 2.3 to display'a stop indication.

I shall assume further that, after atrain has proceeded over track 3T from one main track to "the other, atrainman restores switches [W and 2W=to their normal position, but that a "car ;is :left standing on section ab. Current from rtranslformer, lF' is therefore shunted by the train, :so thatlrelay JXB and transformer 2F are deienergized. With transformer 2F deenergized, relayifiiRgisalsddeenergized. Both signals Island .4 28 therefore continue to display a stop indication until the car has been removed from track 3T.

Although I have herein shown and described only one form of apparatu embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope ,of my invention.

Having thus described my invention, what I claim is:

1. In traffic protection apparatus for a stretch .of railway in which two main tracks are interconnected by a crossover track, the combination comprising, a pair pfinsulated joints in each end .of said crossover track one joint of each of said pairs located between the rails of the adjacent .main track and the other joint of each of said pairs located in the other side of said crossover track, a third pair of insulated joints at an intermediate point between said first and second pairs of insulated joints for dividing ,said crossover track into a first and a second section, a transformer having a primary winding connected through an asymmetric unit across the rails of said first section adjacent said third pair of insulated joints and having .a secondary winding connected in multiple ,with a direct current relay across the rails of ,said second section adjacent said third pair of insulated joints, a secondasymmetric unit connected across the opposite end of said second section, a source of alternating current connected in multiple with a second direct current relayiacross the opposite end of said first section, and ,trafiic governing means for said two main tracks controlled by said first andsecond direct current relays.

2. In traific protection apparatus forastretch of railway in which two main tracks areintercgnnected by a crossover track, the combination comprising, a pair of insulated joints in each end of said crossover track .one joint of eachof said pairs located between the rails of the adjacent main track and theother joint of each of said pairs located ,in the other side of said crossover track, a third pair .of insulated joints at anintermediate point between said first and second pairs of insulated joints ,foridividing said crossover track into a first and a second section, .a transformer lhavinga primary winding connected th u h an asymmetr ,un tac s th rail of said-first section adjacent said third pair of insulated joints, a track circuit for said second section including a secondary winding .of said transformer and the railsiof said second section,

a source of alternatingcurrent connected in multiple with a directqcurrent relay across the rails of the opposite end of said first section, and

traffic governing means for said two main tracks controlled by .said direct current .relay and by said track, circuit ,-for said second section.

3. In combination, a stretchof railway track including a firstand a second section, a transformer having a primary winding connected through an asymmetric unit across the rails of said first ,section, a track circuit for said second section including a secondary winding of said transformer and the railsof said second section, a source of alternating current connected in multiple with adirect current relay .across the rails of said first section, and traflic governing means for said stretch of track controlled'by said direct current relay and by said track circuit for said second section.

.4. In trailic protection apparatus for a stretch of railway trackdncluding a first and a second section, the combination comprising, a transformer havin a primary winding connected through an asymmetric unit across the rails of said first section and having a secondary winding connected in multiple with a direct current relay across the rails of said second section, a second asymmetric unit connected across the rails of said second section, and a source of alternating current connected in multiple with a second direct current relay across the rails of said first section.

5. In combination, a section of railway track, a source of alternating current connected in multiple with a direct current track relay across the rails of one end of said section, a transformer having a primary winding connected through an asymmetric unit across the rails of the other end of said section, and trafiic governing means controlled by current from the secondary winding of said transformer and by said track relay.

6. In traflic protection apparatus for a stretch of railway track including a first and a second section, the combination comprising, a transformer having a primary winding connected across the rails of said first section and having a secondary winding connected in multiple with a direct current relay across the rails of said 6 second section, an asymmetric unit connected in series with said primary winding for passing current from a given rail to the opposite rail of said first section, a second asymmetric unit connected across the rails of said second section for passing current between the rails of said second section in the opposite direction to that in which current is passed by said first asymmetric unit between the rails of said first section, a source of alternating current connected in multiple with a second direct current relay across the rails of said first section, and traffic governing means controlled by said first and second direct current relays.

LESTER E. SPRAY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,815,960 Young July 28, 1931 2,176,612 Pflasterer Oct. 17, 1939 

